<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // delete操作符返回一个布尔值： true指删除成功，否则返回false. 
        // 通过 var, const 或 let 关键字声明的变量无法用 delete 操作符来删除。
        const name = "Lydia";
        let age = 21;

        console.log(delete window.name);
        console.log(delete window.age);
    </script>
</body>

</html>